/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.solr.schema;

import org.apache.lucene.index.AtomicReaderContext;
import org.apache.lucene.index.IndexableField;
import org.apache.lucene.search.FieldCache;
import org.apache.lucene.search.SortField;
import org.apache.lucene.util.BytesRef;
import org.apache.lucene.queries.function.FunctionValues;
import org.apache.lucene.queries.function.ValueSource;
import org.apache.lucene.queries.function.docvalues.BoolDocValues;
import org.apache.lucene.queries.function.valuesource.OrdFieldSource;
import org.apache.lucene.util.CharsRef;
import org.apache.lucene.util.mutable.MutableValue;
import org.apache.lucene.util.mutable.MutableValueBool;
import org.apache.solr.search.QParser;
import org.apache.lucene.analysis.Analyzer;
import org.apache.lucene.analysis.Tokenizer;
import org.apache.lucene.analysis.tokenattributes.CharTermAttribute;
import org.apache.solr.response.TextResponseWriter;
import org.apache.solr.analysis.SolrAnalyzer;

import java.util.Map;
import java.io.Reader;
import java.io.IOException;

/**
 *
 */
public class BoolField extends PrimitiveFieldType {
	@Override
	public SortField getSortField(SchemaField field, boolean reverse) {
		field.checkSortability();
		return getStringSort(field, reverse);
	}

	@Override
	public ValueSource getValueSource(SchemaField field, QParser qparser) {
		field.checkFieldCacheSource(qparser);
		return new BoolFieldSource(field.name);
	}

	// avoid instantiating every time...
	protected final static char[] TRUE_TOKEN = { 'T' };
	protected final static char[] FALSE_TOKEN = { 'F' };

	// //////////////////////////////////////////////////////////////////////
	// TODO: look into creating my own queryParser that can more efficiently
	// handle single valued non-text fields (int,bool,etc) if needed.

	protected final static Analyzer boolAnalyzer = new SolrAnalyzer() {
		@Override
		public TokenStreamComponents createComponents(String fieldName,
				Reader reader) {
			Tokenizer tokenizer = new Tokenizer(reader) {
				final CharTermAttribute termAtt = addAttribute(CharTermAttribute.class);
				boolean done = false;

				@Override
				public void reset() throws IOException {
					done = false;
				}

				@Override
				public boolean incrementToken() throws IOException {
					clearAttributes();
					if (done)
						return false;
					done = true;
					int ch = input.read();
					if (ch == -1)
						return false;
					termAtt.copyBuffer(
							((ch == 't' || ch == 'T' || ch == '1') ? TRUE_TOKEN
									: FALSE_TOKEN), 0, 1);
					return true;
				}
			};

			return new TokenStreamComponents(tokenizer);
		}
	};

	@Override
	public Analyzer getAnalyzer() {
		return boolAnalyzer;
	}

	@Override
	public Analyzer getQueryAnalyzer() {
		return boolAnalyzer;
	}

	@Override
	public String toInternal(String val) {
		char ch = (val != null && val.length() > 0) ? val.charAt(0) : 0;
		return (ch == '1' || ch == 't' || ch == 'T') ? "T" : "F";
	}

	@Override
	public String toExternal(IndexableField f) {
		return indexedToReadable(f.stringValue());
	}

	@Override
	public Boolean toObject(IndexableField f) {
		return Boolean.valueOf(toExternal(f));
	}

	@Override
	public Object toObject(SchemaField sf, BytesRef term) {
		return term.bytes[term.offset] == 'T';
	}

	@Override
	public String indexedToReadable(String indexedForm) {
		char ch = indexedForm.charAt(0);
		return ch == 'T' ? "true" : "false";
	}

	private static final CharsRef TRUE = new CharsRef("true");
	private static final CharsRef FALSE = new CharsRef("false");

	@Override
	public CharsRef indexedToReadable(BytesRef input, CharsRef charsRef) {
		if (input.length > 0 && input.bytes[input.offset] == 'T') {
			charsRef.copyChars(TRUE);
		} else {
			charsRef.copyChars(FALSE);
		}
		return charsRef;
	}

	@Override
	public void write(TextResponseWriter writer, String name, IndexableField f)
			throws IOException {
		writer.writeBool(name, f.stringValue().charAt(0) == 'T');
	}
}

// TODO - this can be much more efficient - use OpenBitSet or Bits
class BoolFieldSource extends ValueSource {
	protected String field;

	public BoolFieldSource(String field) {
		this.field = field;
	}

	@Override
	public String description() {
		return "bool(" + field + ')';
	}

	@Override
	public FunctionValues getValues(Map context,
			AtomicReaderContext readerContext) throws IOException {
		final FieldCache.DocTermsIndex sindex = FieldCache.DEFAULT
				.getTermsIndex(readerContext.reader(), field);

		// figure out what ord maps to true
		int nord = sindex.numOrd();
		BytesRef br = new BytesRef();
		int tord = -1;
		for (int i = 1; i < nord; i++) {
			sindex.lookup(i, br);
			if (br.length == 1 && br.bytes[br.offset] == 'T') {
				tord = i;
				break;
			}
		}

		final int trueOrd = tord;

		return new BoolDocValues(this) {
			@Override
			public boolean boolVal(int doc) {
				return sindex.getOrd(doc) == trueOrd;
			}

			@Override
			public boolean exists(int doc) {
				return sindex.getOrd(doc) != 0;
			}

			@Override
			public ValueFiller getValueFiller() {
				return new ValueFiller() {
					private final MutableValueBool mval = new MutableValueBool();

					@Override
					public MutableValue getValue() {
						return mval;
					}

					@Override
					public void fillValue(int doc) {
						int ord = sindex.getOrd(doc);
						mval.value = (ord == trueOrd);
						mval.exists = (ord != 0);
					}
				};
			}
		};
	}

	@Override
	public boolean equals(Object o) {
		return o.getClass() == BoolFieldSource.class
				&& this.field.equals(((BoolFieldSource) o).field);
	}

	private static final int hcode = OrdFieldSource.class.hashCode();

	@Override
	public int hashCode() {
		return hcode + field.hashCode();
	};

}
